There are a number of wheeled devices which are used to haul various articles such as boat trailers which are used to haul boats, flat bed trailers which are used to haul automobiles, trucks, farm equipment, etc., small trailers which are used to haul lawn mowing equipment, motorcycles, snowmobiles, and the like.
In order to haul loads, trailers need to provide a bed or load-bearing platform which is spaced above the ground by a suitable clearance distance. Moreover, it is generally desired to maintain such beds or load-bearing platforms level during transportation, so that loads provided thereon do not shift.
Loading trailers with loads which cannot be easily lifted can be difficult. In order to do so, trailers are often tilted or tipped upward at their front ends so that their back ends become positioned near the ground. Such a procedure can become dangerous when the center of mass of a heavy load being pulled onto the trailer passes over the wheel axle and the weight thereof causes the trailer to level itself.
Trailers have been developed to include hinged rear sections which can be tilted separately so that the rear of such trailers can be lowered near the ground while the front of such trailers can remain level and optionally secured to a towing vehicle.
The tilting of trailers or trailer sections to lower the rear portion thereof near the ground is limited by the height of the trailer beds or platforms over the wheel axle. This clearance height dictates the angle at which the rear portion of a trailer can be aligned with respect to the ground. For loads which have a low ground clearance, it may not be possible to achieve a suitable trailer tilt angle which will prevent such loads from bottoming out when they are pulled or pushed onto a trailer.
The present invention provides a suspension system for trailers and other wheeled vehicles which allows the beds or platforms of such devices to be lowered.